const utils = {
    getSearchParam: function () {
        var searchURL = window.location.search;
        searchURL = searchURL.substring(1, searchURL.length);
        var targetPageId = searchURL.split("&")[0].split("=")[1];
        return targetPageId;
    },
    zipImg: function (file, callBack) {
        const name = file.name; //文件名
        const reader = new FileReader();
        reader.readAsDataURL(file);
        reader.onload = (e) => {
            const src = e.target.result;
            const img = new Image();
            img.src = src;
            img.onload = (e) => {
                const w = img.width;
                const h = img.height;
                const quality = 0.2; // 默认图片质量为0.92
                //生成canvas
                const canvas = document.createElement('canvas');
                const ctx = canvas.getContext('2d');
                // 创建属性节点
                const anw = document.createAttribute("width");
                anw.nodeValue = w;
                const anh = document.createAttribute("height");
                anh.nodeValue = h;
                canvas.setAttributeNode(anw);
                canvas.setAttributeNode(anh);

                //铺底色 PNG转JPEG时透明区域会变黑色
                ctx.fillStyle = "#fff";
                ctx.fillRect(0, 0, w, h);

                ctx.drawImage(img, 0, 0, w, h);
                // quality值越小，所绘制出的图像越模糊
                const base64 = canvas.toDataURL('image/jpeg', quality); //图片格式jpeg或webp可以选0-1质量区间
                callBack(base64);
            }
        }
    },
    jump: function (url, query) {
        let path = `${url}.html`;
        if (query) {
            path = path + `?name=${query}`;
        }
        window.location.href = path;
    },
    setItem: function(key, item) {
        var base = new this.base64();
        const string = JSON.stringify(item);
        const encodeString = base.encode(string);
        localStorage.setItem(key, encodeString);
    },
    getItem: function(key) {
        var base = new this.base64();
        const data = localStorage.getItem(key);
        if(data) {
            const decodeData = base.decode(data);
            return JSON.parse(decodeData);
        }
    },
    clearLocalStorage: function() {
        localStorage.clear();
    },
    base64: function() {
        // private property  
        _keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
    
        // public method for encoding  
        this.encode = function(input) {
            var output = "";
            var chr1, chr2, chr3, enc1, enc2, enc3, enc4;
            var i = 0;
            input = _utf8_encode(input);
            while(i < input.length) {
                chr1 = input.charCodeAt(i++);
                chr2 = input.charCodeAt(i++);
                chr3 = input.charCodeAt(i++);
                enc1 = chr1 >> 2;
                enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
                enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
                enc4 = chr3 & 63;
                if(isNaN(chr2)) {
                    enc3 = enc4 = 64;
                } else if(isNaN(chr3)) {
                    enc4 = 64;
                }
                output = output +
                    _keyStr.charAt(enc1) + _keyStr.charAt(enc2) +
                    _keyStr.charAt(enc3) + _keyStr.charAt(enc4);
            }
            return output;
        }
    
        // public method for decoding  
        this.decode = function(input) {
            var output = "";
            var chr1, chr2, chr3;
            var enc1, enc2, enc3, enc4;
            var i = 0;
            input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");
            while(i < input.length) {
                enc1 = _keyStr.indexOf(input.charAt(i++));
                enc2 = _keyStr.indexOf(input.charAt(i++));
                enc3 = _keyStr.indexOf(input.charAt(i++));
                enc4 = _keyStr.indexOf(input.charAt(i++));
                chr1 = (enc1 << 2) | (enc2 >> 4);
                chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
                chr3 = ((enc3 & 3) << 6) | enc4;
                output = output + String.fromCharCode(chr1);
                if(enc3 != 64) {
                    output = output + String.fromCharCode(chr2);
                }
                if(enc4 != 64) {
                    output = output + String.fromCharCode(chr3);
                }
            }
            output = _utf8_decode(output);
            return output;
        }
    
        // private method for UTF-8 encoding  
        _utf8_encode = function(string) {
            string = string.replace(/\r\n/g, "\n");
            var utftext = "";
            for(var n = 0; n < string.length; n++) {
                var c = string.charCodeAt(n);
                if(c < 128) {
                    utftext += String.fromCharCode(c);
                } else if((c > 127) && (c < 2048)) {
                    utftext += String.fromCharCode((c >> 6) | 192);
                    utftext += String.fromCharCode((c & 63) | 128);
                } else {
                    utftext += String.fromCharCode((c >> 12) | 224);
                    utftext += String.fromCharCode(((c >> 6) & 63) | 128);
                    utftext += String.fromCharCode((c & 63) | 128);
                }
    
            }
            return utftext;
        }
    
        // private method for UTF-8 decoding  
        _utf8_decode = function(utftext) {
            var string = "";
            var i = 0;
            var c = c1 = c2 = 0;
            while(i < utftext.length) {
                c = utftext.charCodeAt(i);
                if(c < 128) {
                    string += String.fromCharCode(c);
                    i++;
                } else if((c > 191) && (c < 224)) {
                    c2 = utftext.charCodeAt(i + 1);
                    string += String.fromCharCode(((c & 31) << 6) | (c2 & 63));
                    i += 2;
                } else {
                    c2 = utftext.charCodeAt(i + 1);
                    c3 = utftext.charCodeAt(i + 2);
                    string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
                    i += 3;
                }
            }
            return string;
        }
    }
};


